Pressurized metered dose inhalers (pMDI) may be used for delivering medication in the form of aerosols to patients. The route of delivery of the medicament using such inhalers may be oral or nasal.
Such an inhaler commonly comprises a canister containing the medicament aerosol formulation, and an actuator with a delivery passage. The canister contains the aerosol formulation, either as a solution or suspension, in the form of one or more drugs and propellant, and optionally excipients, selected from co-solvents, surfactants, stabilizing substances (for chemical or physical stability) and flavourings. The canister also comprises a metering valve arranged to deliver a metered dose of the medicament on actuation of the inhaler.
The actuator typically comprises a housing, generally made of a plastic material, within which the canister is located. A portion of the canister will usually project above the actuator housing.
In oral inhalers the actuator has a delivery passage in the form of a mouthpiece that is placed in the patient's mouth and through which the medicament passes on being dispensed. The patient places the mouthpiece in their mouth and breathes in, creating an air flow from the actuator through the mouthpiece and into the mouth and lungs. At the same time the patient actuates dispensation of the medicament from the canister. Actuation may occur as a result of inhalation by the patient or the patient may manually actuate the inhaler, for example, by depressing the projecting portion of the canister further into the housing. Nasal actuators operate in a similar fashion, but instead of a mouthpiece the actuator is provided with a nosepiece for delivery of the medicament to the nasal passages. In the case of nasal medicament delivery, there is not a need for the concurrent inhalation of air, however.
WO-A-98/031411 discloses an aerosol inhalation device that is manually operated and comprises a holding part for receiving an aerosol container with a valve and outlet tip, an inspiratory part and a member for passage of aerosol.
US-A-2003/0089368 discloses nozzles for aerosol propellant systems, and more particularly aerosolization spray nozzles for metered dose inhalers.
U.S. Pat. No. 3,361,306 discloses an aerosol device for dispensing a liquid containing a medically active ingredient dissolved or suspended therein.
WO-A-99/25407 discloses an actuator for an inhaler for administering medicament by inhalation.
GB-A-2,143,283 discloses applicators for dispensing medicaments from a pressurised dispensing container.
GB-A-2,170,430 is concerned with improvements relating to spray nozzles, particularly of the kind that are used to dispense a fine spray of liquid.
GB-A-1,021,739 relates to a device for use in inhalation therapy with aerosols.
GB-A-2,366,519 discloses a dispensing apparatus for use with pressurised dispensing containers and, in particular, an apparatus for dispensing orally inhaled medicinal products in aerosol form.